Phospholipases A2 as biomarkers in ARDS

Predictive value of plasma sICAM-1 and sP-Selectins in the risk of death in patients with acute respiratory distress syndrome

Background

To evaluate the predictive value of sICAM-1 and sP-Selectins in the risk of death in a prospective cohort of adult acute respiratory distress syndrome (ARDS).

Methods

Adult ARDS patients were included. Plasma sICAM-1, sP-Selectins, and inflammatory cytokines (TNF-α, IL-1b, IL-6, IL-8, and IL-17A) were detected in ARDS subjects. The correlation between different factors and the potential of sICAM-1 and sP-Selectins as endothelial markers to predict the risk of deathfrom ARDS was analyzed.

Evolution of interfacial mechanics of lung surfactant mimics progression of acute respiratory distress syndrome

How acute respiratory distress syndrome progresses from underlying disease or trauma is poorly understood, and there are no generally accepted treatments resulting in a 40% mortality rate. However, during the inflammation that accompanies this disease, the phospholipase A2 concentration increases in the alveolar fluids leading to the hydrolysis of bacterial, viral, and lung surfactant phospholipids into soluble lysolipids. We show that if the lysolipid concentration in the subphase reaches or exceeds its critical micelle concentration, the surface tension, γ, of dipalmitoyl phosphatidylcholine (DPPC) or Curosurf monolayers increases and the dilatational modulus, [Formula: see text], decreases to that of a pure lysolipid interface. This is consistent with DPPC being solubilized in lysolipid micelles and being replaced by lysolipid at the interface. These changes lead to [Formula: see text] which is the criterion for the Laplace instability that can lead to mechanical instabilities during lung inflation, potentially causing alveolar collapse. These findings provide a mechanism behind the alveolar collapse and uneven lung inflation during ARDS.

Pathogenesis of Multiple Organ Failure: The Impact of Systemic Damage to Plasma Membranes

Multiple organ failure (MOF) is the major cause of morbidity and mortality in intensive care patients, but the mechanisms causing this severe syndrome are still poorly understood. Inflammatory response, tissue hypoxia, immune and cellular metabolic dysregulations, and endothelial and microvascular dysfunction are the main features of MOF, but the exact mechanisms leading to MOF are still unclear. Recent progress in the membrane research suggests that cellular plasma membranes play an important role in key functions of diverse organs. Exploration of mechanisms contributing to plasma membrane damage and repair suggest that these processes can be the missing link in the development of MOF. Elevated levels of extracellular phospholipases, reactive oxygen and nitrogen species, pore-forming proteins (PFPs), and dysregulation of osmotic homeostasis occurring upon systemic inflammatory response are the major extracellular inducers of plasma membrane damage, which may simultaneously operate in different organs causing their profound dysfunction. Hypoxia activates similar processes, but they predominantly occur within the cells targeting intracellular membrane compartments and ultimately causing cell death. To combat the plasma membrane damage cells have developed several repair mechanisms, such as exocytosis, shedding, and protein-driven membrane remodeling. Analysis of knowledge on these mechanisms reveals that systemic damage to plasma membranes may be associated with potentially reversible MOF, which can be quickly recovered, if pathological stimuli are eliminated. Alternatively, it can be transformed in a non-resolving phase, if repair mechanisms are not sufficient to deal with a large damage or if the damage is extended to intracellular compartments essential for vital cellular functions.